Container with a flexible inner tank

ABSTRACT

919,587. Storing liquefied gases. CONCH INTERNATIONAL METHANE Ltd. May 8, 1961 [May 21, 1960; June 23, 1960; Sept. 22, 1960], No. 16611/61. Class 8(2). [Also in Group XXXIII]. A container for storing or transporting a liquefied gas at low temperature and at atmospheric pressure, &#39; comprises a rigid outer shell 2, e.g. formed by the inner hull of a double hull ship or by the inner hull in combination with the cofferdams of the ship, which is internally lined with a heat insulating material 6, e.g. balsawood or quippo, and an inner tank 11 consisting of a rigid top wall 10 and flexible side and bottom walls 8, 9 secured to the top wall, the latter being supported by the shell 2 and the side and bottom walls 8, 9 being supported by the inner surface of the heat insulating material 6. The inner tank is preferably made of aluminium or stainless steel, the side and bottom walls being in the form of foil. The top wall 10 is preferably supported on wooden blocks 12 secured to the shell 2, or is supported by cables or chains from a deck structure 4 of the ship, Fig. 2. (not shown); the space 15 between the wall 10 and the deck structure 4 is filled with glass wool. The wall 10 is provided with a trunk 17 which is insulated at 18 and may be secured to the deck structure 4 or slidably disposed relative thereto. The walls 8, 9 are preferably corrugated. A pump seat, Fig. 5 (not shown), located at the bottom of the tank 11 comprises two metal blocks secured to the respective sides of the bottom wall 9, the block facing the shell 2 having a projection which fits into a recess in a hardwood block on the shell.

Nov. 3, 1964 KATSURO YAMAMOTO 3,155,266

CONTAINER WITH A FLEXIBLE INNER TANK Filed May 15. 1961 Inventor KG ZLSUPO Va mamozo United States Patent "ice 3,155,266 CQNTAINER WITH A FLEXIBLE INNER TANK Katsuro Yamamoto, Nalranoku, Tokyo, lapan, assignor to Conch International Methane Limited, Nassau, Bahamas, a Bahamian company Filed May 15, 1961, Ser. No. 110,085 Claims priority, application Japan May 21, 1960 15 t'llairns. (Cl. 220--15) This invention relates to a container for storing or transporting a liquefied gas at low temperature and at about atmospheric pressure inparticular for storing or transporting liquefied methane or liquefied natural gas.

The temperature at atmospheric pressure of liquefied methane or natural gas is about minus 160 degrees centigrade. In order to prevent evaporation of the liquefied gases during storage and transport it is important to keep the influx of ambient heat to the cold liquid in the container as low as possible. This can be done by providing the container with a suitable heat insulating material.

Many metals lose their strength and ductility at such low temperatures as minus 160 degrees centigrade. Therefore special metals should be used for those parts of the container which are in direct contact with the cold liquid. Examples of such special metals are aluminum and stainless steel. As those metals are rather expensive and as the containers are often very large it is important to use only thin layers of those expensive metals.

The temperature of the container will vary between ambient temperature (container in empty condition) and minus 160 degrees Centigrade (container in loaded condition). Consequently large contractions and expansions of parts of the container are to be expected.

It is a main object of the invention to provide a container which can be easily assembled in an inexpensive way, which is light in construction and in which the smallest possible quantity of special metals not losing strength and ductility at very low temperatures is used.

Therefore the container according to the invention comprises a rigid outer shellinternally lined with a heat insulting material and an inner tank in the space enclosed by said heat insulated shell, said inner tank consisting of a rigid top wall and flexible side and bottom walls secured to said rigid top wall, the rigid top wall being supported ,by the rigid outer shell or by an elementfixed to said outer shell and the flexible side and bottom walls being supported by the inner surface of the heat insulating material lining the rigid outer shell internally.

The container according to the invention will now be described with reference to the drawings in which:

FIGURES 1 and 2 show cross sections of two different embodiments of the container according to the invention.

FIGURES 3 and 4 show cross-sections of two diiferent constructions for supporting the rigid top wall of the inner tank.

FIGURE 5 shows a pump seat for use with the container according to the invention.

A rigid outer shell 2 made of a suitable metal such as steel as internally lined with a heat insulating material 6 such as balsawood, quippo or any other heat insulating material suitable for use at low temperatures. In the space enclosed by the rigid heat insulated outer shell 2 an inner tank 11 is present. The inner tank 11 comprises a rigid top wall 1%, and flexible side and bottom walls 8 and 9 secured to the rigid top wall 10. The rigid top wall It is supported by the rigid outer shell 2 or by elements fixed to the shell 2. The flexible side and bottom walls 8 and 9 are supported by the inner surface of the heat insulating material 6. The side and bottom walls 8 and 9 are made of a metal having substantial cold resistance. Suitable metals are amongst others aluminium or stainless steel. In

order to obtain a reasonable flexibility the walls 8 and 9 3,155,265 Patented Nov. 3, 1964 should be made sufiiciently thin for example in the form of a foil.

The rigid top wall 10 should also be made of a metal not losing its strength and ductility at the low temperature of the liquid in the container for example of aluminium. The top wall 10 can be supported along its edge by means of blocks 12 made of wood or another suitable material of low heat-conductivity. If necessary extra blocks 13 can be used above the top wall 10. Theblocks 12 and 13 are secured to the inner surface of the rigid outer shell 2. Instead of the blocks 12 and 13 cables or chains 14 can be used for supporting the rigid top Wall 10. Each of the cables 14 is fixed with one end to the rigid top wall It) and with the other end to a deck structure 4. Said deck-structure 4 is secured to the outer shell 2. The space 15 between the top wall 10 and the deck structure 4 is filled with a suitable heat insulating material for example with glass-wool. An opening 16 serves for loading and unloading the inner tank 11 but also as an outlet of vapor derived from vaporization of the liquid cargo. Preferably the rigid top wall 10 is provided with a trunk 17. Layers of heat insulating material 18 lining the trunk 17 are preferably present. The trunk can be secured to the top wall 10 and to the deck-structure 4.

As the vertical walls 3 of the tank 11 are flexible the vertical expansion and contraction of the inner tank 11 due to temperature changes is accommodated by those walls 8. Furthermore the expansion and contraction of the rigid top wall 10 is accommodated by the special way of supporting it and by the provision of a peripheral spacing.

The inner tank 11 can be constructed as such and then be lowered as a whole into the space enclosed by the heatinsulated shell 2. Also it is possible to remove the tank 11 as a whole from the space for example after a certain period of use. In other words the inner tank 11 can be easily inspected both before and after a period of use.

The side walls 8 and the bottom wall 9 of the inner tank 11 are constructed of thin flexible membranes such as aluminium foil. Said walls 8 and 9 are deflected due to the internal pressure in the inner tank 11 into close contact with the inner surface of the heat-insulating material 6.

As the walls 8 and 9 of the inner tank 11 are flexible the inner tank 11 would not be able to retain its proper configuration by itself if the walls 8 and 9 were not secured to rigid top wall 10. In other words the rigid'top wall 10 prevents the inner tank. 11 from collapsing.

The walls 8 and 9 are preferably corrugated so that they may readily yield under the internal pressure in the tank 11 into close contact with the heat insulating material 6.

The heat insulating material 6 must be able to take up the weightof the liquid cargo in the inner tank 11. Consequently said heat insulating material 6 must have a rather high compressive strength. As the top wall 10 is rigid the heat insulating material on top of the wall 10 need however not have a high compressive strength.

The trunk 17 may be rigidly secured to the deckstructure 4. Instead it may be made slidable so that it can move vertically with respect to the deckstructure 4.

In the case that the container according to the invention is destined for use in a ship the rigid outer shell 2 can be formed by the inner hull of a double hull ship or by the cotierdams of such a ship in combination with said inner hull.

In FIGURES 1 and 2 the rigid outer shell 2 is constructed as an inner hull of a ship. The inner hull is parallel to and rigidly secured to an outer hull 1.

It is remarked that the'invention relates both to land storage containers and to ships for transporting liquefied gases.

In containers for storing liquefied gases it is desirable to make use of a deep-well pump located near the bottom of the container for unloading the container. In the case of a container according to the invention special measures have to be taken-to support the pump near the flexible bottom wall 9 of the inner tank 11. Therefore (see FIGURE a rigid pump seat structure 19 is provided. This structure 19 is supported by a pillow block 29, said pillow block 29 being in its turn supported by a pillow block support 21 made of hardwood. The pumpseat structure 19 and the pillow block 20 are made of a metal not losing its strength and ductility at very low temperatures. The pillow block 20 and the pump seat 19 are secured to the flexible bottom wall 9 of the inner tank 11 by means of a suitable adhesive. The pillow block 2i) is provided on the underside thereof with a projection 22 adapted to be fitted into a recessed groove formed in the top face of the pillow block support 21 with the result that any forces acting upon the pump seat structure 19 due to the operational motion or vibration of the pump and/ or the stirring of the liquid are taken up through the pillow block 20, the support 21 by the outer shell 2, which is sturdy and strong. It will also be recognized that the pillow block support 21, formed of hardwood has a thermal insulating capacity to prevent heat from flowing into the interior of the inner tank 11.

I claim:

1. A container for storing a liquefied gas at low temperature and at about atmospheric pressure comprising a rigid outer shell internally lined with a heat insulatingmaterial and an inner tank in the space enclosed by said hcatinsulated shell, said inner tank consisting of a rigid top wall and flexible side and bottom walls secured to said rigid top wall, the rigid top wall being supported by an element fixed to the rigid outer shell in a manner to permit lateral contraction and-expansion of said 'top wall relative to the outer shell, and the flexible side and bottom walls being supported by the inner surface of the heat insulating material lining the rigid outer shell internally.

2. A-container as claimed in claim 1 in which the rigid top wall of the inner tank is suspended by cables, one end of each of said cables being secured to the rigid top wall of the inner tank and the other end of 'each of said, cables being secured to a deck-structure of the rigid outer shell.

"3..A container as claimed-in claim 2 in which the rigid top-wall of the inner tank is provided with a trunk.

4. A container as claimed in claim 3 in which the trunk is secured to a deckstructure of the rigid outer shell.

5. A container as claimed in claim 3 in which the trunk is slidably mounted with respect to adeck structure of the rigid outer shell so thatsaid trunkcan only move vertically.

6. A container as claimed in claim 3 in which the trunk is provided with heat insulating material.

7. A container as claimed in claim 2. in which the space above the rigid top wall of the inner tank is provided with heat insulating material.

S. A container for storing a liquefied gas at low temperature and at about atmospheric pressure comprising a rigid outer shell internally lined with a heat insulating material and an inner tank in the space'enclosed by said heat insulated shell, said inner tank consisting of a rigid top wall and flexible side and bottom walls secured to said rigid top wall, the rigid top wall being supported by an element fixed to the-rigidouter shell and the-flexible side and bottom walls being supported by the inner surface of the heat insulating material lining the rigid outer shell internally, the rigid outer shell being provided along its inner surface with supporting elements made of a material of low heat-conductivity, which supporting elements support the rigid top wall along its edge.

9. A container as claimed in claim 8 in which the rigid top wall of the inner tank is provided with a trunk.

10. A container as claimed in claim 9 in which the trunk is secured to a deck-structure of the rigid outer shell.

11. A container as claimed in claim 9 in which the trunk is slidably mounted with respect to a deck structure of the rigid outer shell so that said trunk can move only vertically.

12. A container as claimed in claim 9 in which the trunk is provided with heat insulating material.

13. A container as claimed in claim 8 in which the space above the rigid top wall of the inner tank provided with heat insulating material.

14. A container for storing a liquefied gas at low temperature and at about atmospheric pressure comprising a rigid outer shell internally lined with a heat insulating material and an inner tank in the space enclosed by said heat insulated-shell, said inner tank consisting of a rigid top wall and flexible side and bottom Walls secured to said rigid top wall, the rigid top wall being supported by the rigid outer shell and the flexible side and bottom walls being supported by the inner surface of the heat insulating material lining the rigid outer shell internally, the inner tank being provided with a pump seat comprising a first metal block secured to the inner surface of the bottom wall and a second metal block secured to the outer surface of the bottom wall opposite the first metal block, said second block being located in a space in the bottom layer of heat insulating material and being supported and held in a fixed position by means of a wooden block .in-said space.

15. A container for storing a liquefied gas at low temperature and at about atmospheric pressure comprising a rigid outer shell internally lined with a heat insulating material and an inner tank in the space enclosed by said heat insulated shell, said inner tank consisting of a rigid top wall and flexible side and bottom Walls secured to said rigid top wall, the rigid top Wall being supported by an element fixed to the rigid outer shell and the flexible side andbottom walls being supported by the inner surface of the heat insulating material lining. the rigid outer shell internally, the inner tank being provided with a pump seat comprising a first metal block secured to the inner surface of the bottom wall and a second metal block secured to the outer surface of the bottom wall opposite the first metal block, said second block being located in a space in the bottom layer of heat insulating material and being supportedand fixed by means of a Wooden block in said space.

References Cited in the file of this patent UNITED STATES PATENTS 

1. A CONTAINER FOR STORING A LIQUEFIED GAS AT LOW TEMPERATURE AND AT ABOUT ATMOSPHERIC PRESSURE COMPRISING A RIGID OUTER SHELL INTERNALLY LINED WITH A HEAT INSULATING MATERIAL AND AN INNER TANK IN THE SPACE ENCLOSED BY SAID HEAT INSULATED SHELL, SAID INNER TANK CONSISTING OF A RIGID TOP WALL AND FLEXIBLE SIDE AND BOTTOM WALLS SECURED TO SAID RIGID TOP WALL, THE RIGID TOP WALL BEING SUPPORTED BY AN ELEMENT FIXED TO THE RIGID OUTER SHELL IN A MANNER 